Instrumentation following intradural tumor resection: A case analyses and literature review

INTRODUCTION

Approximately 45% of spinal canal tumors are intradural; roughly 40% are extramedullary and 5% are intramedullary in location.[9] Typically, they are resected utilizing a posterior approach, which may destabilize the spine warranting simultaneous fusion.

After the resection of intradural tumors, the cervical spine appears to be more vulnerable to instability than the thoracic or lumbar spine (e.g. risk of post laminectomy kyphosis).[3] As the width of laminectomy increases, the risk of postoperative biomechanical stability increases.[2,8] The pediatric population is especially susceptible to such postoperative spinal deformity.

CASE PRESENTATIONS

Case presentation #1

A 37-year-old female presented with 1 year of neck pain and bilateral upper extremity radiculopathy. An MRI revealed an intramedullary lesion extending from C2 to C6 with associated syrinx [Figure 1 and Table 1]. She underwent C2–C7 laminectomy with lateral mass instrumented fusion. Pathology revealed ependymoma. Postoperatively, her strength was preserved, and upright X-rays showed good instrumentation placement [Figure 2].

Close

Figure 1:: (a) Sagittal T2-weighted MRI showing an intradural, intramedullary lesion extending from C2 to C6 with an associated syrinx. (b) Axial T2-weighted MRI at the level of C4 showing the expansion of the spinal cord.

Export to PPT

Close

Figure 2:: (a) Upright lateral cervical spine X-ray showing preserved sagittal balance. (b) AP cervical spine X-ray showing good hardware placement. The left C3 screw was removed intraoperatively due to poor purchase.

Export to PPT

Table 1:: Summary of instrumentation cases and outcomes.

Case presentation #2

A 75-year-old female presented with several weeks of paresis and urinary incontinence. The MRI revealed five intradural tumors between T10 and T12 [Figure 3]. She underwent a laminectomy of T10–12 with intradural resection of the tumors, followed by a pedicle screw instrumented fusion from T9 to L1. Upright X-rays [Figure 4] postoperatively showed good hardware placement, and her lower extremity weakness gradually improved, allowing her to be discharged to an inpatient rehabilitation facility on the 10^th postoperative day.

Close

Figure 3:: (a) Sagittal T2 MRI of the thoracic spine showing five intradural extramedullary masses at the levels of T10–T12. (b) Axial T1 MRI with contrast showing uniformly enhancing circumscribed lesion at the level of T10, causing severe mass effect on the spinal cord with near-complete flattening.

Export to PPT

Close

Figure 4:: (a) Postoperative upright thoracic spine AP X-ray showing good hardware construct utilizing five screws on the left and two screws on the right. (b) Lateral plain film showing good sagittal alignment and disc spacing.

Export to PPT

Case presentation #3

A 52-year-old male presented with a 1-year history of back pain radiating to the posterior thighs and feet. The MRI revealed an intradural extramedullary lesion at the L4 level [Figure 5]. He underwent an L3–4 laminectomy, left L4–5 facetectomy, and L4–5 instrumented fusion with pedicle screws/rods. The pathology revealed a schwannoma, the WHO Grade I. Postoperatively, upright X-rays showed the good placement of hardware [Figure 6]. He did develop a wound dehiscence 2 months postoperatively that was successfully treated with oversewing and antibiotics.

Close

Figure 5:: (a) Lumbar sagittal T2 MRI showing an intradural extramedullary lesion at the level of L4. (b) Lumbar axial T1 MRI with contrast at the level of the L4–5 intervertebral disc showing a mixed enhancing lesion extending into the left L4–5 neural foramina.

Export to PPT

Close

Figure 6:: (a) Standing lumbar spine AP X-ray showing good hardware placement. (b) Lateral standing plain film showing preserved sagittal alignment.

Export to PPT

DISCUSSION

When resection of intradural spinal tumors necessitates the significant disruption of posterior column elements, patients may require simultaneous fusion to avoid instability. The cervical spine appears most vulnerable followed by the thoracic and then lumbar spine.[4]

Preoperative cervical kyphosis increases the risk that after cervical tumor resection, a cervical fusion will be warranted. Fusion should also be considered when C2 posterior elements are disrupted, as this leads to further instability.[6] Knafo et al. demonstrated that patients undergoing laminectomy or laminoplasty at 4 or more levels, or those at the thoracolumbar junction, especially in patients <30 years of age, are at increased risk of postoperative sagittal deformity.[7] The rates of postoperative deformity appear to be similar for laminectomy and laminoplasty.[5]

Removal of one-third to half of a facet joint complex, especially in the lumbar spine, does not cause significant instability.[1] When gaining lateral access to the dura, however, with multilevel facetectomies and pediculotomies, the need for fusion is increased.

In our series of cases, “open” surgical approaches offered more optimal tumor removal versus minimally invasive techniques. The increased instability associated with posterior column disruption was mitigated by performing simultaneous instrumented fusions with successful prevention of postoperative spinal deformity.

CONCLUSION

Cervical spine location, pre-operative kyphosis, patient age, and number of levels decompressed appear to be the most significant risk factors for developing post-operative instability. Concomitant instrumented fusion following posterior spinal decompression for intradural tumor removal allows for maximal resection while preventing post-operative spinal deformity.